The present invention relates to a Bi-CMOS element, specifically relates to a manufacturing method for a Bi-CMOS which is allowed to manufacture simultaneously a bipolar element and a CMOS element by the formation of trenching on one substrate.
Heretofore, the bipolar element and the CMOS element have been respectively manufactured separately, and a general manufacturing process of the bipolar element is shown in FIG. 1(A)-(G), while a general manufacturing process of CMOS element which is a memory element is shown in FIG. 2(A)-(F).
In manufacturing a bipolar element, firstly as shown in FIG. 1(A), a silicon oxide (SiO.sub.2) layer 2 is formed on a p-type silicon substrate 1 thereafter said oxide layer 2 is selectively etched and the only predetermined portion of p-type silicon substrate 1 is exposed, and as shown in FIG. 1 (B) a n-type impurity of high density is doped on the exposed portion of the p-type silicon substrate 1, and then is diffused so that a N.sup.+ buried layer 3 for the decrease of continuous resistance of collector is formed. Then as shown in FIG. 1(C), said silicon oxide layer 2 is removed, after growing a n-type epitaxial layer 4 as shown in FIG. (D) a thermal oxidation film 5 is formed on the surface of said epitaxial layer 4 by a predetermined thickness, then said thermal oxidation film 5 is selectively etched by a photoetching, and a phosphor (P) which is a n-type impurity is doped at said selectively etched portion, then is diffused to the interior so that an isolated region 6 is formed. Then as shown in FIG. 1(E), said thermal oxidation film 5 is selectively etched by a photoetching, after p-type impurity is doped a base region 7 is formed by a thermal diffusion, then as shown in FIG. 1(F) said thermal oxidation film 5 is selectively etched, after a phosphor oxide film is doped then an emitter region 8 and a collector region 9 are formed respectively.
Then as shown in FIG. 1(G), said thermal oxidation film 5 is removed, and a metal oxide film 10 is formed, and said metal oxide layer 10 is selectively etched by a photoetching and then metal oxide window is obtained, thereafter a metal is deposited over said metal oxide window and then electrode terminals 11,12,13 are drawn out from said base region 7, emitter region 8 and collector region 9, so that the manufacturing of a bipolar element is completed.
On the other hand, in manufacturing a CMOS element which is a memory element, firstly as shown in FIG. 2(A), an oxide layer 22 is formed on the surface of n-type silicon substrate 21, thereafter as shown in FIG. 2(B) said oxide layer 22 is selectively etched by masking and etching process, and a p-type well 23 is formed by diffusing a p-type impurity through said selectively etched portion, then as shown in FIG. 2(C), after said oxide layer 22 is selectively etched, a p-type impurity such as boron is diffused, so that a source region 24 and a drain region 25 of p-channel are formed. Then, as shown in FIG. 2(D), a source region 26 and a drain region 27 of n-channel are formed by diffusing a phosphor which is a n-type impurity within said p-type well 23, then as shown in FIG. 2(E), after said oxide is removed, another oxide layer 22 is formed again, and said oxide layer 22 is selectively etched then a gate region 28 is formed, so that a boron is filled within said gate region 28 for the reinforcement of threshold voltage thereafter a polycrystal silicon 29 is fused therewith. Then as shown in FIG. 2(F), after the electrode window is opened and then aluminum is deposited over entire surface, the masking and etching are carried out thereby unnecessary portions connected between the source, drain and gate are removed so that the manufacturing of CMOS element is completed.
However, in such a conventional manufacturing method of bipolar element and CMOS element, there has been no way except to manufacture separately the bipolar element and CMOS element respectively, therefore in case where they are applied to a communication and various electronic appliances which the bipolar element and CMOS element are simultaneously required, the number of the parts are increased, consequently there has been a defect that their assembling work becomes troublesome or the like due to the increase of the number of their parts.